Vapor heated roll



June-23, 1953 w. T. R. KINRAIDE ETAL 2,643,099

VAPOR .HETED ROLL Filed Nov. 4, 1950 ,4. @mM/@RN IN V EN TORS m. mm WL mHE RC. MR ME 0T HL TA W M Ad U D u. aw W A TTORNE Y Patented .une 23,14953 UNITED STATES PATENT oFFlcE Avaron HEATED aoLL William Thomas ReedKinraide, Bolton, Mass., and 'Walter C. Eberlin, Wilmington, Del., as*signers. t0 E. I. du Pont de Nemours & 00.31.1- muur-z Wilminaton.Deli... a corporation. of Dela- Ware.

Application November 4, 1950, Serial N0.. Y194,086

of the paper machine and pass. the wet pulp con!V tinously from roll toroll along a serpentine. path. The rolls must be maintained' at. asufficiently high ltemperature to dry the web duringI passage throughthe drier, but the. temperature should not be so high that the qualityof the paper is impaired. However, the permissible temperature. range isrelatively wide.

Steam is the usual heating medium because of the convenience and readycontrol of the temperature at which heat is supplied to the roll. Thetemperature at which the heat. of con` densation of the steam is givenup is controlled by regulating the pressure of the steam supply. Thesteam condenses at constant temperature Within the hollow roll and thetemperature drops occurring during heat transfer to the outer rollsurface need be of concern if the saturated steam temperature is asuitable number of de.- grees above the minimum effective temperaturefor. the roll. Other vapors, such as paracymenr-z vapor, may be usedwhen condensation temperatures above 200 C. are required, in order toavoid the excessive pressures which would be required with steam.

The drying of some types of textile bers and fabrics requires morecareful temperature con-` trol because the maximum temperature which canbe used without injuring the material is lower than that of paper.However, drying can still be performed successfully over a fairly widerange of temperatures, and ordinary steam.- heated rolls can be used.

A much more difficult heating problem arises when material is subjectedAto special treatment within a narrow temperature range.. For example,the properties of certain types of syn thetic yarns are greatly improvedby stretching the yarn in a moist condition, drying under tenE sion, andthen conditioning the yarn at an elevated temperature to eliminate allor most. of the residual shrinkage. and conditioning must all beperformed within relatively narrow temperature ranges in Order Thestretching, .drying 1 Chim (Cl. 257-9-5) to obtain optimum properties,and temperature uniformity within the optimum range is necessary toobtain uniform yarn properties.

The continuous aftertreatment of synthetic yarns is accomplishedconveniently and economically on a plurality of running ends of yarn inthe for-m of a warp. Drawing, drying, relaxing, and heat treatments ofvarious sorts are performed customarily by passing the yarn around c oneor more heated rolls, driven at; the proper speed. One difculty withprocessing a plu.- raiity of running ends or yarn in warp form is inmaintaining uniformity of treatment of each individual running end.Consequently, in hot `roll. processing, yarn uniformity necessitatesthat the temperature of roll surfaces contacting the yarn be maintainedWithin stringent limits in order to keep the individual ends of yarn atthe same temperature.. The roll surface should be maintained within pluser minus C. of the optimum temperature at all points of contact, withloads. varying from afew yarn ends te as vmany as 1000 or more, and atsurface speeds up to 1000 yards per minute or higher.

It h asA been found to be impossible to achieve such .close control oftemperature withy ordinary steam-heated rolls having Cylindrical wallsof uniform: thickness.. The outside surface temperature of a typical121/2' inch diameter steel roll having walls .1/2 inch thick variedunder even moderate loads by 13- across the working surface, was alsouneven in temperature under no load conditions, and a change intemperature of 13 C. occurred at some places on the roll when theloading conditions were changed from no load to moderate load.`

Non-.uniformity of temperature. in the case of ordinary.' rolls hasbeeen found to be caused principally by the insulating effect of a layerof water of unequal thickness formed by the condensing steam. Water is amuch poorer conductor of heat than. the metal of the roll. Thecondensate is thrown off: of the en@ plates 0f the rolls by the Anaricirotation of the rolls and, flows over the inside 0f. the cylindricalsur-face to the condensate rcmeval Pipe, Where the water is removed..The layer is thinnestY on the end plates and at .the point or points ofremoval. and the temperature of theoutside of the roll will v.moet.nearlyapprenti-1 the Steam Ytemporature at thesel places. Thetemperature at other places the outsidey of the roll will be lower andwill vary depending upon the thickness of the condensate lav. Thisthickness willv vary not only with. the. cation but to. an even greater3 extent, with the load on the roll, as this determines the rate atwhich condensation occurs.

It is an object of the present invention to provide a roll heated bysteam or other vapor which, when rotated at sufficient speed to preventcondensate from accumulating in a pool Yat the bottom of the vaporchamber, has substantially uniform temperature characteristics at allpoints on the outside working surface under all conditions of operation.Other objects of the invention will become apparent from the followingdescription and the drawing.

The objects of the invention are accomplished by forming the vaporchambenwith a taper, so that the chamber tapers along the axis of theroll from a larger diameter at one end to a smaller diameter at theother end, and providing a condensate collection trough at the largerend of the chamber and means for removing condensate out of the chamberfrom the trough. Preferably a cooling trough is located at the oppositeend of the chamber from the condensate collection trough.

Specific embodiments of the invention will now be described withreference to th'e drawing,

in which,

Figure 1 is a sectional elevation of one formof roll, the section beingtaken along the axis of the roll,

Figure 2 is a transverse section taken on line 2-2 of Figure 1, and

Figure 3 is a sectional elevation, corresponding to Fig. 1, showing amodified form of the invention.

The roll shown in Fig. 1 comprises a cylindrical wall I0, a circularfront end II, a circular rear end I2 attached to a hollow supportingaxle I3, and a condensate pipe I 4 passing through the axle. The Wall Idecreases uniformly in thickness from the front end to the rear end toprovide an axial taper to the vapor chamber I5 formed by the cylindricalwall I0 and the ends II and I2. A condensate trough IS is provided inthe wall I0 adjacent to the front end I I. This trough rings the insideof the wall to trap condensate and reduce heat transfer from the end IIto the wall. Another similar trough I'I is cut into the inside of thewall adjacent to the rear end I2. The trough forms a receptacle for andcollects condensate carried along the sloping inside surface of wall I0by centrifugal forces resulting from rotation of the roll. Condensatepipe I4 is bent downward into trough Il' to remove condensate collectedtherein.

Steam or other vapor is introduced into chamber I5 through passageway I9and annular space 2D surrounding condensate pipe I4 inside of hollowaxle I3. It is desirable to surround this steam passage with insulation2I. The axle is supported on bearings 22 and 23, and is rotated bysuitable means engaging a gear 24 mounted on the axle between the twobearings.

In the embodiments shown in the drawings the the condensate pipe isstationary, and a suitable bearing 25 is arranged to support it at theinner end of the axle. As shown. in Fig. 2, the end 21 of condensatepipe I4 is preferably bent in the opposite direction from the directionof 4rotation of the roll to form a scoop lwhich helps to re movecondensate from the collection trough I1. Of course the condensate pipecouldl be arranged to rotate with the roll, which would simplify theconstruction, but this is less desirable from the standpoint ofcondensate removal.

A modified form of the invention is shown in 4 Fig. 3 in which thecylindrical walls 30 of the Vapor chamber decrease in thickness from therear of the chamber and are thinnest at the front. With this arrangementcondensate is carried tothe front end of the chamber, in a directionopposite to that of the embodiment shown in Fig. 1. Hence the condensatepipe 3| must extend to the front of the roll with the end 32 projectinginto a condensate collection trough 33 to remove the condensate. Thecircular front end 34 of the roll is provided on the inside with abearing 35 to support the condensate pipe. Another bearing 36 isarranged to support the "condensate pipe where it passes into the vaporchamber of the roll through the circular rear end 31. This bearing alsosupports the end of vapor pipe 38 surrounding the condensate pipe. Steamor other vapor is admitted into the chamber through this pipe 38 andpassageway 39 through the bearing 36. A condensate trough 40 ispreferably provided to reduce heat transfer from the end 3l to thecylindrical walls 3U. In other respects this embodiment of the inventionis similar to the one shown in Fig. 1.

Suitable means for lubricating the various bearings and for providingvapor-tight joints have been shown in the drawing. Since these arewell-known in the art and form no part of the invention, they have notbeen described.

The advantages of rolls in accordance with this invention over ordinarysteam-heated rolls, having a simple cylindrical steam chamber, are asfollows:

(1) The tapered or frusto-conical shape of the vapor chamber, and thecollection trough, greatly reduce the condensate build-up onheat-transfer surfaces, required in the case of ordinary rolls to causecondensate to flow tol the point of re-` moval. As soon as condensateforms on the interior heat-transfer surface, the centrifugal forcesresulting from rotation of the roll cause the condensate to move towardthe larger end of the chamber and into the trough. This keeps thecondensate nlm on the heat-transfer surface thin, so that the insulatingeffect is kept low. As a result, the outside roll temperature is onlyslightly affected in going from no load or partial load to full load.

(2) The condensate layer is also more uniform in thickness and isthinnest where the metal wall is thickest. The volume of flowingcondensate increases as the point of removal is approached, but the wallis simultaneously decreasing in thickness. The decreasing resistance toheat transfer of the wall offsets the increasing resistance of thecondensate layer and provides for uniform heat transfer to the outsideworking surface. The temperature has been found to be substantiallyuniform over the whole working Surface under both no load and full loadconditions.

(3) Condensate collect-ing in the troughs at each end of the chamberreduces heat conduction from the end plates of the roll to the ends ofthe outside Working surface and avoids non-uniformity of temperaturefrom this source.

The temperature uniformity achieved in actual operation with asteam-heated steel roll in accordance with this invention, 121/2 inchesin diameter and 251/2 inches long, is shown in the table. Thetemperatures were measured on the outside surface of the rotating rollwith a special instrument developed for the purpose. N o load means thatno material was being treated and heat losses from the rotating rollwere ap- Inches from end 10 15 20 No Load C" 165 165 165 165 Full Load C158 158 158 158 The cylindrical wall of the roll used in the above testtapered from 11/3 inch thick at the thick end to 'V8 inch thick at thethin end, and the roll speed was approximately 800 rotations per minute.It is seen that excellent uniformity of surface temperature was obtainedat both no load :ind full load conditions. At considerably lower rollspeeds it might be desirable to increase the taper. The temperaturedifference between no load and full load conditions (7 C.) can bereduced appreciably by reducing the Wall thickness or by using a metalof higher conductivity than steel, such as copper or aluminum.

Since many different embodiments of the invention may be made withoutdeparting from the spirit and scope thereof, it is to be understood thatthe invention is not limited by the specic illustrations except to theextent defined in the following claim.

What is claimed is:

A rotatable, vapor-heated, cylindrical roll roll adapted for high speedcontinuous treatment of material at a uniform temperature within plus orminus 4 C. of an optimum temperature over the entire working surface ofthe roll which comprises a wall having a cylindrical outer surfaceconstituting the Working surface of the roll, circular end platesattached to each end of said cylindrical wall and enclosing avapor-heating chamber Within said Wall, a hollow supporting axleattached to one only of said end plates in axial alignment with saidroll, bearings supporting said axle in horizontal position for rotationof said roll, said cylindrical Wall being tapered uniformly in thicknessfrom end to end to provide a vapor chamber having a gradually increasingdiameter from one of said end plates to the other end plate, condensatecollection troughs ringing the inner side of said Wall adjacent to eachof said end plates, an a stationary condensate removal pipe passingaxially through said supporting axle into said chamber with the chamberend of the pipe located in the condensate trough at the larger diameterend of said chamber, said pipe end being bent in the opposite directionfrom the direction of rotation of the roll to act as a scoop forremoving condensate.

WILLIAM THOMAS REED KINRAIDE. WALTER C. EBERLIN.

References Cited'in the ille of this patent UNITED STATES PATENTS NumberName Date 1,575,249 Berry et al. Mar. 2, 1926 FOREIGN PATENTS NumberCountry Date 304,108 Great Britain Jan. 17, 1929

